How Hybridization Can Boost the Economics of Energy Storage

European energy storage players are taking a leading role in developing hybrid systems that can cover several applications at once, improving investment returns.

Companies such as Bosch and Younicos have recently unveiled projects that combine different storage technologies in a single system.

In Braderup, a town in northern Germany, for example, Bosch has supplied a 2-megawatt/2-megawatt-hour Sony lithium-ion battery for short-term grid stabilization. Vanadis Power added a 325-kilowatt/1-megawatt-hour vanadium redox flow unit to the system, allowing the residents of Braderup to save energy or sell excess electricity when prices are higher.

Along with managing and installing the project, Bosch has taken responsibility for marketing the batteries in the frequency regulation market, trading on the electricity exchange and stabilizing the power grid. It also developed and configured the control electronics, system integration and testing of the different operating criteria.

Younicos is also combining lithium-ion with sodium-sulfur and zinc-redox or vanadium-redox chemistries, as well as advanced lead-acid. All undergo very stringent testing to ensure they are suitable for the specific applications for which they’re being used.

One such Younicos hybrid system helped the Azores island of Graciosa end its dependence on diesel. The community of 4,500 now uses sun and wind for power, thanks in part to a Younicos energy management system that controls 2.6 megawatts of combined lithium-ion and sodium-sulfur battery storage.

Hybridization could help make storage more competitive, said Stephen Prince, chief revenue officer at Younicos.

“The industry is evolving, and the advantage of hybrid energy storage is that it adds the ability to balance power needs with energy needs,” said Prince.

Anil Srivastava, chief executive of the battery company Leclanché, contends that storage combinations are often better than tying to settle on a single optimal technology for a project.

“We would achieve more by using smart software to integrate the strengths of different storage technologies seamlessly into hybrid systems,” he said in a recent press statement. “This applies to both stationary applications and e-mobility.”

And although Bosch, Younicos, and a few other companies are looking at combining battery chemistries, others are getting entirely different technologies to work together.

Fraunhofer ISE says it has successfully tested a hybrid system that combines thousands of batteries and heat storage systems into a virtual storage system. The agent-based operation system has been developed and tested within the institute’s SmartEnergyLab facility.

There, agent-based controllers manage a co-generation plant that also includes water storage, a heat pump with phase-change storage, and a lithium-ion battery system.

Hybridization is also a viable solution for dealing with the storage demands of electric vehicles, according to Paul Nicolae Borza, a storage expert with the European Cooperation in Science and Technology.

Borza says it makes sense to use a supercapacitor to start up a vehicle and then use another battery to supply the energy for driving. He also says combining supercapacitors with chemistries such as lead-acid can significantly improve battery longevity when used for black starts and braking energy recovery, as well as giving older technologies a new lease on life.

Leesa Lee, senior vice president of product management and marketing at Greensmith, an energy management systems developer, said that with hybridization, “you have multiple use cases. Different batteries are good for different applications.”

“There are some batteries that work better in more power-centric applications where you have high power and short duration. And there are other batteries that are more suited to energy-centric [uses], with a longer discharge cycle,” said Lee.

Combining technologies with different capabilities allows developers to stack various applications on a single asset, she said.

The upfront cost might be slightly higher due to differing technologies and the need for advanced system management. However, the return on investment is often better because of shared balance-of-plant and installation costs.

“Being able to have multiple types of batteries that you can control to do multiple things is very valuable,” Lee said.

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